(1) Field of the Invention
The present invention relates to a method of measuring a height and of detecting obstacles, to a radioaltimeter, and to an aircraft.
(2) Description of Related Art
The invention thus lies in the technical field of detecting obstacles from on board an aircraft.
An aircraft is usually provided with a plurality of flight instruments. Such flight instruments may include a radioaltimeter that serves to determine the height between the aircraft and the overflown ground.
Such a radioaltimeter may include a generator-receiver for generating and receiving signals such as radiowaves, the signal generator-receiver co-operating with signal transceiver means and with display means. The transceiver means may comprise either an antenna suitable for transmitting and receiving a signal, or else two antennas, namely a first antenna for transmitting a signal and a second antenna for receiving a signal.
Under such circumstances, the generator-receiver causes a signal to be transmitted towards the ground by the transceiver means. The signal is reflected on the ground and then picked up by the transceiver means which in turn informs the generator-receiver. Knowing the speed of propagation of the signal and the duration of the go-and-return path of the signal from the transceiver means to the ground then from the ground to the transceiver means, the generator-receiver deduces the height of the aircraft.
Certain radioaltimeter means trigger an alarm as a function of the measured height.
A radioaltimeter is thus an instrument that is very useful. Nevertheless, that instrument is not designed to detect obstacles other than the overflown terrain.
Various other devices are known having the function of detecting obstacles.
For example, document FR 2 908 547 suggests using radar sensors cyclically transmitting signals to a central unit, the signals being presented on a display after being compared with predefined warning thresholds.
Document JP 2008/014643 also seeks to detect objects by radar waves.
Document EP 1 617 243 presents a car radar device seeking to reduce the disturbances caused by the ground.
Document FR 2 773 609 presents a device for providing assistance in aerial navigation, which device is provided with a radioaltimeter providing the height of an aircraft.
Document FR 2 297 466 relates to an excessive descent speed alarm device that makes use of a radioaltimeter for measuring altitude relative to the ground.
Document US 2010/0299067 discloses a collision avoidance device that makes use of a radiofrequency radar.
Thus, the above state of the art presents a radioaltimeter for measuring the height of a vehicle relative to the ground, and also various devices for detecting and locating obstacles in order to summarize the situation by indicating the distance between the aircraft and said obstacles.